Question

7(x+y)³-5(x+y)²-2(x+y)

如题，不是因式分解，是算出来，要步骤

Answer 1

7(x+y)³-5(x+y)²-2(x+y)
解：设 x＋y＝m
原式＝7m³－5m²－2m
＝m（7m²－5m－2）
＝m（7m＋2）（m－1）
＝（x＋y）（7x＋7y＋2）（x＋y－1）
＝[（x＋y）²－x－y]（7x＋7y＋2）
＝（x²＋2xy＋y²－x－y）（7x＋7y＋2）
＝7x³+14x²y+7xy²-5x²-5xy-2x+7x²y+14xy³+7y³-5xy-5y²-2y
＝7x³+21x²y+21xy²+7y³-5x²-10xy-5y²-2x-2y
望采纳，谢谢啊

Answer 2

=7（x^3+y^3+3x^2y+3xy^2）-5(x^2+y^2+2xy)-2x-2y
=7x^3+7y^3+21x^2y+21xy^2-5x^2-5y^2-10xy-2x-2y

Answer 3

7(x+y)³-5(x+y)²-2(x+y)
=7(x^3+3x^2y+3xy^2+y^3)-5(x^2+2xy+y^2)-2x-2y
=7x^3+21x^2y+21xy^2+7y^3-5x^2-10xy-5y^2-2x-2y

Answer 4

=7(x+y)(x²+2xy+y²)-5(x²+2xy+y²)-2(x+y)
=7x³+7y³+21x²y+21xy²-5x²-5y²-10xy-2x-2y

Answer 5

7(x+y)³-5(x+y)²-2(x+y)
=（x+y)[7(x+y)²-5(x+y)-2]
=(x+y）（7x²+14xy+7y²-5x-5y-2）
=7x³+14x²y+7xy²-5x²-5xy-2x+7x²y+14xy³+7y³-5xy-5y²-2y
= 7x³+21x²y+21xy²+7y³-5x²-10xy-5y²-2x-2y